Method of producing bridging matrix for endless sound bands



' y 1 1946- H. WESTERKAMP 2, 04,761

METHOD OF PRODUCING BRIDGING MATRIX FOR ENDLESS SOUND BANDS Filed Oct. 29, 1941 A g Awe/7 za:

Patented July 23, 1946 llIETHOD OF PRODUCING BRIDGING MA- TRIX FOR ENDLESS SOUND BANDS Hugo Westerkamp, Koln-Poll, Germany; vested in the Alien Property Custodian Application October 29, 1941, Serial No. 417,027 In Germany July 8, 1940 3 Claims. (01. i -48.3)

l The invention relates to a method of producing endless sound bands with several sound tracks running parallel to the edge of the band and being mechanically reproducible.

It is known to produce endless sound bands of said kind by connecting the ends of an open-- ended sound band with the aid of a bridging matrix. The known method proposes to produce the bridging matrix from the original sound band, before a pressing or stamping matrix is made from the original. In most cases, this cannot be carried out, because the sound record on the original sound band is ,completely destroyed at the portion from which the bridging matrix has been produced.

According to the invention, the ends of the open-ended sound band, with a number of parallel sound tracks produced by a pressing or stamping process, are connected by means of a bridging matrix which has been produced from the original sound band or from a copy thereof.

Advantageously, the bridging matrix is obtained by producing patrices from the ends of the original matrix, which patrices are cut, fitted together, soldered, and engraved with continuous sound tracks, and from the one piece obtained in this manner, the bridging matrix is produced, for example, by a galvanoplastic moulding process.

This bridging matrix may be manually brought to engage the sound tracks at the ends of the duplicated open-ended sound band, which ends are fitted together or are arranged so as to overlap each other for the purpose of being connected, whereupon the sound grooves at each end are brought into engagement with the corresponding sound ribs of the bridging matrix. But this bringing into engagement is rather difficult and in order to make it easier, the original sound band is provided, according to the invention, on both sides of the out part and outside the sound track bundle, with marks, for example in the form of depressions. These depressions are formed in producing the pressing matrix and the openended sound band made from this matrix as well as in producing the bridging matrix, the marks thus formed on the ends of the sound band being brought to engage the corresponding marks formed in the bridging matrix when connecting the ends of the sound band.

An example of the method according to the invention is diagrammatically illustrated in the accompanying drawing, in which:

Fig. 1 is a perspective view of an original sound record.

Fig. 2 is a perspective view of a reproduction matrix.

v Fig. 3 is an elevation of the patrices.

' Fig. 4 is an elevation of the patrices after being joined and with a part of the connecting lines having been cut.

Fig. 5 is an elevation of the bridging matrix.

Fig. 6 is a diagrammatic view showing the employment of the bridging matrix in connecting the ends of the duplicate sound record.

Fig. 1 shows an endless original sound band constituting the starting material for the method according to the invention. The original sound band consists, for example, of a wax band, i. e. a carrier layer covered with a Wax layer, into which a. sound, groove is continuously cut in known manner, this sound groove having a length amounting to a multiple of the length of the sound band and running parallel to the edge of the band. I is the carrier layer of the original sound band, 2 is the wax layer, and $3 is the sound groove cut into the wax layer.

From the endless original sound band there are produced the duplicate open-ended sound bands by stamping, pressing, casting or the like by means of a matrix. For this purpose, the endless, original sound band is cut for example at 4 so as to obtain an open-ended band, from which is made, for example by a galvanoplastic process, an open-ended original matrix 5 (Fig. 2) serving to produce an open-ended patrix which, on the other hand, serves to produce an openended pressing or stamping matrix.

By cutting the endless original sound band, the sound tracks 3 have been interrupted; the cutting of the original sound band, and especially the production of the matrix and of the patrix, result in a small loss of the band and, consequently, in a. loss of a part Of the sound record so that, when the ends of the individual duplicate sound bands produced are fitted together, the associated sound tracks will no longer exactly run in the same lines. But it is absolutely necessary that the sound tracks should run exactly in the same lines so as to prevent the reproducing needle from jumping out of the sound track or entering another sound track.

In order to prevent this, the ends of the sound band are connected according to the invention by means of a bridging matrix which is produced in the following manner:

Patrices are produced from each of the ends a and b of the original matrix 5 (Fig. 2), for example by a galvanoplastic process; these two patrices are shown at 6 and I in Fig. 3. The

3 edges of the ends of the band 5, originally irregular, owing to the galvanoplastic production, are advantageously cut straight before being placed in the galvanic bath. The parts 6 and 1 of the patrices are then aligned with the sound tracks, fitted and soldered together. The transverse and longitudinal alignment is advantageously effected by means of an optical magnifying method. After the parts 6 and I of the patrix have been soldered together or connected in some other manner so as to form one piece, the sound tracks, though transversely aligned,.being still separated by the solder joint or the like; are connected by engraving connecting tracks so as toobtain continuous sound tracks. Fig. 4 shows the connected parts 6 and 1 of the patrix with one half of the sound tracks connected by engraved connecting tracks and the other half of the sound tracks still separated by the solder joint or the like.

Thereupon the connected parts 6 and (of the patrix are used to producaalso by a galvano plastic process, a pressing or stamping matrix 8 (Fig. which represents the desired bridging matrix.

The ends of the individual duplicate open-snob ed sound band, produced, for example by a pressing or stamping process, are now fitted together on the bridging matrix in such a manner that the sound grooves on the ends of the band engage the corresponding parts of the ribs of the bridging matrix, as far as fitting parts exist on the two ends of the band, on the one hand, and on the bridging matrix, on the other hand. This engagement, may be effected manually. The free ends of the band are advantageously cut obliquely along the original separating line 4 (Fig. 1) and are, preferably ehamfered, brought to overlap band, to bring the sound ribs of the bridging matrix into engagement with the sound grooves in the free ends of the sound band, which is thus eiTected automatically.

What is claimed is:

1.. A method of producing endless sound bands having a number of mechanically reproducible sound tracks running parallel to the edge of the band, which comprises preparing from an original sound record band having a number of mechanically reproducible sound tracks running parallel to the edge thereof, an open-ended matrix, preparing open-ended duplicate sound records from said matrix, preparing patrices corresponding to end portions of the matrix, aligning and uniting the end of said patrices corresponding to the open ends of the matrix and forming across the union continuous engraved record lines each other, as illustrated in Fig. 6, in which the bridging matrix is again marked 8 and the ends of the duplicateband are marked 9 and I0. By applying heat and pressure, the ends of the band are united by means of a pressing member I! so as to form an endless band. In this uniting process, the connecting lines of the sound grooves, engraved manually in the production of the bridging matrix, are pressed into the material of the duplicate ound band, so that the endless sound band is also provided with uninterrupted sound grooves at the connecting point.

The engagement of the sound grooves at the free ends of the band in its open-ended form with the sound ribs of the bridging matrix is difficult and requires much time. In order to facilitate this operation, the endless original sound band is provided, according to the invention, on both sides of the cutting line i outside the sound track region with marks, which are moulded in the production of the pressing matrix and of the open-ended sound band made therefrom as well as in the production of the bridging matrix. The marks may, for example, consist of depressions in. the wax layer of the original sound band. In Fig. 1 there are indicated on the right of the cutting place 4 three depressions I2, and on the left of the cutting place three depressions [3. In the original matrix 5 (Fig. 2), these depressions are represented by projections l2, l3, and in the sound band produced in series they are again in the form of hollow depressions. On the other hand, the original depressions form projections in the bridging matrix, so that it is easy, by inserting these projections in the correspond.-

ing depressions. in the free ends of the sound joinin the record lines existing on the patrices, preparing a bridging matrix from the united and engraved patrices, and connecting. the ends of the open-ended duplicate record by employing the bridging matrix to impress the point of connection whereby the sound tracks on the endless duplicate recordare made continuous.

2. A method of producing endless sound bands having a number of mechanically reproducible sound tracks running parallel to the edge of the band from an original sound record band having a number of mechanically reproducible sound tracks running parallel to the edge of said original record band, which comprises forming aligning marks in spaced apart relation along the length of the original record band, preparing from the original record band an open-ended matrix having marks thereon corresponding to said aligning marks, preparing open-ended duplicate sound records fromv said matrix havin at each end locating marks reproducing said align- 1ng marks, preparingpatrices corresponding to end portions of the matrix having thereon marks 1 corresponding to said locating marks, aligning and uniting the ends of said patrices corresponding to the open ends of the matrix andforming across the union continuous engraved record lines joining the record lines existing on the patrices, preparing a bridging matrix from the united and engraved patrices having thereon locating marks corresponding to the marks on said patrices, and aligning the bridging matrix with the ends of the open-ended duplicate records and connecting the said ends while maintaining the alignment and employing the bridging matrix to impress the point of connection whereby the sound tracks on the endless duplicate record are made continuous.

3. A method of producing a bridging matrix for use in duplicating an original endless sound record band having a number of mechanically reproducible sound tracks running parallel to the edge of the band, which comprises preparing from the original record band an open ended matrix, preparing patrices corresponding to the end portions of the matrix, alignin and uniting the 

